Compressor regulator



June l0', 1947. ls. F. EvELYN 2,421,372

` COIPRESSOR REGULATORV Filed Feb. 11, 41944 2 `summa-sneu 1` NVENTOB BY... I

June l0, 1947. s. F. EVELYN V COPRESSOR REGULATOR 2 Sheets-Shoot 2 Y Filed Feb. 11. 1944 ATTORNEY Patented June 10, 1947 COMPRESSOR REGULATOR Steven F. Evelyn, Southampton, Mass., `assigner to Worthington Pump and Machinery Corporation, Harrison, N. J., a corporation of Dela- Application February 11, 1944, Serial No. 521,913

22 Claims.

This invention relates to control apparatus or regulators for internal combustion engine driven compressors, and more particularly to control apparatus for regulating the speed of operation of the engine in conformance with the load demand on the compressor. i y

Compressor units of the type with which the regulator or control apparatus of the present (Cl. B30-9) which regulating means operates independently of a governor actuatedspeed control means of the engine.

With these `and other objects in view,as may appear from the accompanying speciiication, the invention consists of various features of construction and combination of parts, which will invention is employed comprise a. compressor driven by an internal combustion engine. The fluid compressed is discharged by the compressor into a storage tank or receiver from which it is taken to perform the desired work, suchas operating percussive' tools or the like, and in the greater percentage of jobs on which a compressor unit of this type is employedthe load demand is irregular, iluctuating widely at varying intervals. Control of the compressor is provided by unloading mechanism, which unloads the compressor when the`pressure in the receiver reaches a predetermined high degreeI and loads the compressor when the pressure falls below a predetermined low degree, that is,`the degree of pressure required for performing the desired work. When the compressor is unloaded, the engine is slowed to the minimum oridling rate of speed; and when the compressor is` loaded, the engine speed is increased to the maximum speed.

Under certain load conditions, the compressor will unload and load at frequent intervals and the engine will be decelerated and accelerated accordingly, resulting in an unsteady and uneconomical operation of the unit. i

An object of the present invention is therefore to provide means whereby the speed of operation of the engine will be automatically controlled to operate the compressor unit at the most economical speed which will satisfy the load conditions on the unit and prevent operation oi' the unit at a speed in excess of that required by theload c-n the compressor.

Another object of the present invention is to provide a modulating control of the speed of operation of thev engine whereby its speed and, consequently, the speed of operation of the compresser unit is progressively regulated by the compressor discharge pressure, and further to provide means whereby when the compressor is unloaded the engine will be operated at a predetermined minimum speed. f

A further object of the present invention is to provide regulating means for regulating the speed of operation of the engine or motor'by pressure conditions of the compressor discharge be ilrst described in connection with the accompanying drawings, showing a compressor regulator of a preferred form embodying the invention, and the features forming the invention wil be specifically pointed out in the claims.

In the drawings: Figure 1 is a side elevation of a portable internal combustion engine driven compressor unit showing the improved regulator mechanism applied thereto l Figure 2 is a view' partly in side elevation and partly in vertical section of the improved regulating` mechanism.

Figure 3 isa cross-section taken on the line 3--3 ofl Figure 2.

4-'4 of Figure 2.

Figure 5 is a fragmentary vertical section taken at'right angles to the section shown in Figure 2 and also taken on the line 5--5 of Figure `2.

Figure 6 is a fragmentary section "showing the conventional compressor unloading mechanism. Referringmore particularly `to the drawings, the portable compressor unit comprises'al compressor I of theA reciprocating Piston type which may be of any approved construction-weil known in the art andlpurchasable upon the open mar- Figure 4 isacross-section' taken on theline ket. 'I'he compressor lis driven byan internal combustion engine 2 which likewise is of any approved t-ype which may be purchased upon the open market and which receives its operating fuel through an intake manifold, delivering to the intake manifold of the` combustible mixture through a suitable intake pipe 4 in which is po- 3 anism forming the present invention by the discharge pressure of the compressor I.

The compressor I discharges through a suitable discharge I I into the storage tank or receiver I2, as is customary, and from which receiver pressure fluid is drawn to perform the desired work.

As is usual in portable compressor units of this type, the discharge pressure and operation .of the compressor is controlled by the pressure in the receiver I2 and thus when the pressure within the receiver, that is, the Idischarge pressure of the compressor, reaches a predetermined high, a small quantity of the pressure fluid bleeding from the receiver I2 through the pipe or connection I4 will actuate the trigger valve I5. The trigger valve I5 which is of a conventional, wellknown type being clearly shown in prior Patent No. 1,150,915 and is tensioned so that when the pressure of the fluid being delivered thereto through the pipe I4 reaches a predetermined high degree the trigger valve |5 will operate to admit the pressure uid therethrough and to the unloading mechanism |6 through the connection |1. The uloading mechanism I6 is of a conventional type, that being shown in Figure 6 of the drawings comprising a tensioned piston I8 which when pressure fluid is delivered to the cylinder I9 will be forced inwardly to unseat and hold open the discharge valve 20 of a compressor for the purpose of unloading the compressor by permitting the air compressed thereby to be passed back and forth through the compressor.

All of the foregoing described mechanism' is 01d in the art and is well known.

n The regulating mechanism for regulatingl the speed of operation of the engine and consequently the compressor in proportion Awith the load demand comprises a cylinder 2| in which a piston 22 is mounted with limited reciprocatory movement. The movement of the piston 22 is limited by the stop shoulders 23 and 24 formed in the wall structure of the cylinder' 2|. .The piston 22 is urged against the stop 24 by a spring 25 which is tensioned to a predetermined degree necessary to provide a sensitive, highly balanced control for the second throttle valve I0. The piston 22 carries a piston rod 26 which extends through the piston and has a head 21 carried vby the end thereof adjacent to the piston 22. The head 21 is rigidly connected to the piston 22 and engages a diaphragm 28. The diaphragm 28 extends across a chamber 29 formed in the cylinder structure 2|. The chamber 29 is lconnected to the receiver I2 into' which the compressor discharges by a suitable pipe or conduit 30 so that this chamber 28 always receives pressure fluid at the discharge pressure of the compressor I. The

pressure ofthe pressure iiuid'in the chamber 29 acts upon the diaphragm 28 to move the piston 22 upwardly against the tension of the spring 25 and against the tension of the adjustable modulating control spring 3| which is connected to the lever 32. The lever 32 has linkage connection by means of the links 33 and 34 with the throttle valve I8 for operating the throttle valve. The lever 32 is pivotally supported upon a pivot 35 carried by the cylinder 2|, and it has a slip joint coupling member 36 pivotally connected thereto between the .pivot 35 of the lever and the point of connection 31 of the lever with the link 33.-

The slip coupling 36 has a cylindrical bore 38 which slidably receives the upper end of the piston rod 26 so that when the piston 22 is urged or moved upwardly sufficiently to cause contact of the end of the piston rod 26 with the inner end of the bore 38 and is further moved upwardly it will cause upward movement of the portion of the lever 32 between the pivot 35 and its point of connection 31 to the link 33 resulting in a closing movement of the throttle valve I0 with a Consequent retarding of the supply of fuel to the internal combustion engine 2. As the pressure of the fluid in the chamber 28 recedes, the piston will be moved downwardly by action of the spring 25, and the piston rod or stem 26 will slide in the lbore 38, and consequently will not effect movement of the lever 32. The lever 32 will, however, be returned or moved downwardly by action of the spring 3|.

The spring 3| is pivotally connected by a suitable coupling 39 to the lever 32 outwardly of the pivot 35 and the point of connection of the coupling 36 with the lever. The lower end of the spring 3| is engaged by a tension adjusting structure 40 which is preferably `supported from the cylinder 2| in any suitable manner such as by means of the brackets 4I and set screws 42. The tension adjustingmechanism 40 comprises a cage i3r in which is mounted, for vertical movement, a spring engaging nut 44 which is threaded on the coils of the spring 3| and is held against rotation by means of ribs 45 which engage in vertically extending annular grooves 46 formed in the cage 43. An adjusting screw 41 is carried by the cage 43 and is threadably connected to the nut or member 44 so that by turning of the adjusting screw 41 the tension of the spring 3| may be varied.

The nut 44 functions as a secondary adjustment which provides a' change in the rate of the spring 3| by increasing or decreasing the number of inactive coils in the spring. The inactive coils are shown beneath the nut 44 in Figures 2 and 5.

Such spring rate adjustment is desirable in overcoming commercial variations in the control spring, thus making the device uniformly sensitive to predetermined pressure ranges. It is understood that the coils of the spring 3| below the nut 44 are rendered inactive insofar as their action upon the lever 32 is concerned. If the throttle ID closes too suddenly., or too slowly, this action can be corrected by changing the number of active coils of the spring 3| through adjustment of the nut 44. Adjustment of the number of active coils of the spring 3| adjusts the deflection of the spring per unit load, and deflection of this spring 3| controls the position of the throttle valve I0 through the lever 32 and linkage 33 and 34.

Owing to the desired sensitivity to pressure variances of the regulating mechanism, it is highly desirable that friction in the movement of the various elements, and particularly of the piston 22, be reduced to the highest possible minimum and practically eliminated, and for this purpose a novel device or structure is provided to provide positive centered, substantially frictionless movement of the piston 22. By reference to Figure 2 of the drawings, it will be noted that the perimeter of the piston 22 is spaced from the facing wall of the cylinder 2| thus eliminating friction between the piston and the cylinder upon movement of the piston. However, to insure sensitive, accurate operation of the mechanism it is necessary that the piston be accurately centered. A disc 48 is carried by the head structure 21 and consequently is rigidly connected to the piston 22. 'I'he disc 48 is provided with a plurality of circumferentially spaced peripheral recesses 49 in each of which is mounted a bearing ball A50. As shown in Figure 3 of the drawings, the recesses are slightly wider than the diameter of the bearing balls 50, and the bearing balls are supported at the inner ends of the recesses by reduced bearing surfaces 5I thus permitting, limited movement of the bearing balls 5I) in the recesses 49. The bearing balls 59 engage the inner wal-l of the cylinder 2| and they are held against dislodgement from the recesses 49, which as shown in Figure 2 of the drawings extend out through the sides of the disc 48, by resilient spiders 52 one of which is placed upon each side of the disc 48. The spiders 52 comprise a plurality of radiating iiat spring arms 53 gradually decreasing in width towards their outer free ends. The outer free ends of the arms 53 engages the bearing balls 5D so as to yieldably hold them in position with respect to the disc 48, and, consequently, with respect to the piston 22 and yet permit limited movement of the bearing balls relative to the disc and the cylinder for the purpose of eliminating friction and for accurately centering the piston 22 at all times.

The foregoing structure provides a modulating speed control of the engine in accordance with variations in the load demand on thecompressor, that is, 'in accordance with variations in the discharge pressure of the compressor so as to prevent excessive speeding of the engine and compressor at predetermined times, and to provide the most economical operation of the engine in that it will be operated only at the speed required to provide the necessary discharge pressure of the compressor to meet the iluctuating load demand, and thus the number of times that the unit is stopped and started and the compressor unloaded and loaded will be very materially reduced, since without the modulated control just described the compressor would operate until the maximum high pressure was provided in the receiver at which time the compressor would unload to be loaded again when the pressure in the receiver fell below the required load demand.

However, there will betimes when the load demand on the compressor will fall below the degree provided by the modulating control just described, and so as to prevent racing of the engine when the compressor is unloaded by action of the trigger valve I5, mechanism is provided for Voperating the throttle valve I0 independently of movement of the piston 22.

acting upon the diaphragm 64 will move the piston head 62 and its stem IilV and consequently rock the arm 56 upon its pivot to move the rod 54, rock the lever 32, and move the throttle valve I0 to reduce the quantity of fuel delivered to the engine, and, in fact, to cause the engine to operate at its idling speed.

` When the compressor is loaded by action ofthe triggervalve I5, the supply of pressure lluid-to the chamber 65 will be cut off, and the modulating control mechanism will come into effect through the action of the pressure fluid in the chamber 29. The provision of the slip joint 55, and the slip joint connection between the piston stem or rod 26 and the lever 32 will permitindependent, unimpeded operation of the mechanism for operating the second throttle valve I0.

It will be understood that the invention is not to be limited to the specic construction or arrangement of partsshown, but that they may be widely modified within the invention defined'by the claims.

What is claimed is: A,

1. In a speed regulator for an ,engine driven iluid compressor unit having a governor and a throttle valve controlled by the governor, of a second throttle valve operable independently of the governor controlled throttle valve, a pressure actuated modulating speed control device operable upon variances in the discharge pressure of the compressor to vary the setting of said second throttle Valve to regulate the speed of operation of the engine and compressor in response to variances in the discharge pressure ofthe compressor, means to unload the compressor at a` predetermined maximumhigh discharge pressure and to load the compressor at a predetermined low discharge pressure, pressure actuated means operable` when the compressor is unloaded to move said second throttle valve to and maintain it at a predetermined minimum speed position, and means providing `a slip joint in said pressure actuated means operable to maintain the predetermined minimumI speed so as to prevent its in- 4terference with operation of the modulating speed control. y l

2. In a speed regulator for an engine driven fluid compressor unit having a governor and a throttle valve controlled by the governor, of a second throttle valve operable independently of the governor controlled throttle valve, a pressure actuated modulating speed control device operotally mounted arm 5G. Adjustable nut's 51 are provided adjusting the slip joint connection 55.

. The arm 5B is pivotally supported at 58 on an extension or bracket 59 depending from the cylinder 2l and it has a `contact surface 60 formed thereon intermediate its ends which is held into engagement with the stem Blof a piston head.62 by means of a spring 63. The piston head 62 is engaged by a diaphragm El which extends across the chamber 65 formed in the lower end of the cylinder 2|. The chamber 65 is `connected by suitable piping S5 to the. outlet piping or open` ing of the trigger valve I5 and through the trigger valve I5 and `piping I4 to the receiver I2 so that when the compressor I is unloaded by action or operation of the trigger valve I5 fluid under pressure will be delivered to the chamber $5, and

able upon variances in the discharge pressure of the compressor to vary the setting of said second throttle valve to regulate the speed of operation of the engine and compressor in response to variances in the discharge pressure of the compressor, said modulating'speed control device including a pivotally mounted operating lever, linkage` connecting said lever to said second throttle, a piston acted upon by discharge pressure of the compressor, and means providing a slip joint connection between said` piston -and lever.

3. In a speedV regulator for an engine driven uid compressor unit` having a. governor and a throttle valve controlled by the governor, of a second throttle valve operable independently o1' Vthe governor controlled throttle valve, a pressure ances in the discharge pressure of the com-.

pressor, said modulating speed control device in cluding a pivotally mounted operating lever, linkage connecting said lever to said second throttle, a piston acted upon by discharge pressure of the compressor, means providing a slip joint connection between said piston and lever, means to unload the compressor at a predetermined maximum high discharge pressure and to load the compressor at a. predetermined low discharge pressure, a second pressure actuated means, said compressor unloading and loading means controlling delivery of actuating pressure iluid to said second pressure actuated means, and means connecting said second pressure actuated means to said lever to move said second throttle to and maintain it at a. predetermined maximum speed when the compressor is unloaded.

4. In a speed regulator for an engine driven fluid compressor unit having a governor and a throttle valve controlled by the governer, oi' a second throttle valve operable' independently of the governor controlled throttle valve, a. pressure actuated modulating speed control device operable upon variances in the discharge pressure of the compressor to vary the setting of said second throttle valve to regulate the speed of operation of the engine and compressor in response to variances in the discharge pressure of thev compressor, said modulating speed control device including a pivotally mounted operating lever, linkage connecting said lever to said second throttle, a piston acted upon by discharge pressure oi the compressor, means providing a slip Joint connection between said piston and lever, means to unload the compressor at a predetermined maximum high discharge pressure and to load the compressor at a predetermined low discharge pressure, a second pressure actuated means, said compressor unloading and loading means controlling delivery of actuating pressure fluid to said second pressure actuated means, means con-y necting said second pressure actuated means to said lever to move said second throttle to and maintain it at a predetermined maximum speed when the compressor is unloaded, said connecting means constructed and arranged to permit movement of said lever by said piston unimpeded by action of said second pressure actuated means.

5. In a speed regulator for an engine driven iiuid compressor unit having a governor and a throttle valve controlled by the governer, of a second throttle valve operable independently of the governor controlled throttle valve, a pressure actuated modulating speed control device operable upon variances in the discharge pressure of the compressor to vary the setting of said second throttle valve to regulate the speed of operation of the engine and compressor in response to variances in the discharge pressure of the compressor, said modulating speed control device including a pivot-ally mounted operating lever, linkage connecting said lever to said second throttle, a cylinder, a piston in said cylinder, means actuated by discharge pressure of the compressor for moving said piston in said cylinder, means connecting said piston to said lever, means applying a predetermined initial tension on said piston, and tensioning means connected to said lever to apply a. predetermined tension to the lever in opposition to the movement of the lever by said piston.

6. In a speed regulator for an engine driven fluid compressor unit having a governor and a throttle valve controlled by the governor, o! a second throttle valve operable independently of the governor controlled throttle valve, a pressure actuated modulating speed control device oper- 8 able upon variances inthe discharge pressure of the compessor to vary the setting of said second throttle valve to regulate the speed of operation of the engine and compressor in response to variances in the discharge pressure of the compressor, said modulating speed control device including a pivotally mounted operating lever, linkage connecting said lever to said second throttle, a cylinder, a piston in said cylinder, means actuated by discharge pressure of the compressor for moving said piston in said cylinder, means connecting said piston to said lever, means applying a predetermined initial tension on said piston, tensioning means connected to said lever to apply a predetermined tension to the lever in opposition to the movement of the lever by said piston, and adjustable means for regulating the tension applied to said lever.

7. In a speed regulator for an engine driven uid compressor unit having a governor and a throttle valve controlled by the governor, of a second throttle valve operable independently of the governor controlled throttle valve, a pressure actuated modulating speed control device operable upon variances in the discharge pressure of the compressorto vary the setting of said second throttle valve to regulate the speed of operation of the engine and compressor in response to variances in the discharge pressure of the compressor, said modulating speed control device including a pivotally mounted operating lever, linkage connecting said lever to said second throttle, a cylinder, a piston in said cylinder, means actuated by discharge pressure of the compressor for moving said piston in said cylinder, means connecting said piston to said lever, means applying a predetermined initial tension on said piston, tensioning means connected to said lever to apply a predetermined tension to the lever in opposition tothe movement of the lever by said piston, and stop* means formed in said cylinder for limiting'movement of said piston.

8. In a speed regulator for an engine driven iluid compressor unit having a governor and a throttle valve controlled by the governor of a second throttle valve operable independently of the governor controlled throttle valve, a pressure actuated modulating speed control device operable upon variances in the discharge pressure of the compressor to vary the setting of said second throttle valve to regulate the speed of operation of the engine and compressor 'in response to variances in the discharge pressure of the compressor, said modulating speed controldevice including a pivotally mounted operating lever, linkage connecting said lever to said second throttle, a cylinder, a piston in said cylinder, means actuated by discharge pressure of the compressor for moving said piston in said cylinder, means connecting said piston to said lever, means applying a predetermined initial tension on said piston, tensioning means connected to said lever to apply a predetermined tension to the lever in opposition to the movement of the lever by said piston, and a frictionless and universal centering device carried by said piston and engaging second throttle valve operable independently of the governor controlled throttle valve, a pressure actuated modulating speed control device operable upon variances in the discharge pressure'of the compressor to vary the setting of saidsec-l ond throttle valve to regulate the speed o! operation of the engine and compressor" in response to variances in the discharge pressure of the` compressor, vsaid modulating speed control device including a pivotally mounted operatin`g le` ver, linkage connecting said lever to saidsecond throttle, a i cylinder, a ypiston in said cylinder,

means actuated by dischargepressure of the com:

presser for moving said piston in said cylinder,`

means connecting said piston to said lever, means applying a predetermined initial tension on said in dischargepressure of fthecompressor, meansv piston, tensioning means connected t'o said lever* to apply a predetermined tension tothe lever in opposition to the movement of thelever by said Vice carried byl said piston and* engaging said cylinder, said piston being free from peripheraly engagement with said cylinder, said `frictionless and universal centering device comprising a carrying body having a `plurality of `circumferen-` tially spaced recesses in its perimeter, bearing d itl piston, a. frictionless and universal centering deproviding a slip joint connection between said piston andlever.` l l i 12.`In a `speed regulator `for an engine driven fluid compressor having a throttle valve controlled by the governor,`of a second throttle `valve f operable independently of the governor controlled throttle "valve, a pivoted levenlmkage connecting said lever to said second throttle valve, a pistonV lconnected'to said lever onfone side of its pivot, means for moving said piston under fluctuations to unload thecompressor at predetermined maximum high, pressure and to `load the compressor i at predetermined low pressure,imean's connected to said lever at the side of itspivot opposite to Y w `the sideA to which saidvp'istonis c onnected, pressure actuated `means for-moving said last-named i meansftmd a Apressure fluid delivering `conduit; i connecting said pressureactuated means and saidV compressor" loading and-unloading means whereby the compressor 'loading andsunloading `means balls in said recesses, and spring members engag l i, ing said `bearing balls upon each side of saidw carrying body to yieldably maintain the balls inv position to providefa -frictionlessanduniversal` centering of the piston inthe cylinder.- i 10. In a speed regulator fory an engine driven iiuid compressor vunit having agovernor and a i throttle valve controlled by thegovernor, of a second throttle valve operable independently `of4 the governor controlled throttlefvalve, and` aV pressure actuated modulating `speed-control cle-1V vice operable upon variances in`the discharge pressure of the compressor to vary the setting` of saidsecond throttle valve toregulate the speed of operation of the engine and compressor in response to .variances in thedischargepressure `oi."

will control operationof the pressure actuated V1 31-1Iria regulator. for an engine driven fluid Compressor having a throttle valve `conl :I trollediby the governonof a second throttle valve y operable independently ofI the "governor con-` "trolled throttle valve a pivoted lever, linkage the compressor, said modulating speed control device including a pivotally mounted operating lever, linkage connecting saidlever to said`sec' i ond throttle, a` cylinder, a piston in said cylinder,

means actuated byY dischargepiessure of the c0m--` pressoiior moving Vsaid piston insaid cylinderif means lconnecting said piston to said lever, means applying a predetermined initialtension on said piston, means to unload the compressor at a` predetermined maximum high discharge pressure and to load the compressor ata predetermined low discharge pressure, a second pressure actu-f ated means, said compressor unloading and loading means controlling delivery of actuating pressure fluid to said second pressure actuated means,"

and means connecting said second pressureac-- tuated means to said lever to move saidsecond throttle tension and maintain it at a predeter-*i' mined minimum speed when .the compressor is unloaded.

ll. In a speed regulator for ari-engine driven` uid compressor unit having a governor" and ai throttle valve controlled by the governor, of a sec-` ond throttle Valve operable independently of the governor controlled throttlevalve, a pressure ac` p tuated modulating speed control device operable upon variances in the `dischargepressure of the;

compressor to ,vary the settingof said secndi throttle valve to regulate the speedof operation of the engine and compressor in response to variances in the discharge pressure of the compressor, said modulating speed control `device include-` ing a pivotally mounted operating lever,` linkage connecting said lever to said second throttle, a`

cylinder, a piston in said cylinder,` means. actu` ated by discharge pressure ofthe compressorfo'i moving said piston in said cylinder, andi'means connecting said lever `to saidisecond throttle valve, axpiston connected `to said lever on one side of `itspivot, means for moving said piston under iiuctuations in discharge pressure of the compresi sor, means tofunload the compressor at prede` terminedl maximum high pressureand to`load* theccmpressor` at predetermined loW pressure,

i an operating rod connectedv to said lever atthe` side of its" pivot opposite to the side to which said piston isi connected, pressure' actuated means' for moving said rod, a pressure iluld delivery conI duit cohnecting saidpressureiactuated means and said compressor loading land unloading means whereby the compressor loading and unloading vme'ansvvvill control operationofvthe pressure actuated meansy means `providing al slip connection between saidlpistonand lever, and means provid-` ing a `slip connection between saidfrod and lever. 14. In a1 speed regulator for an engine driven iiuid compressor having althrottle valve controlled `by the governor, of asecond throttle valve operable `independently off the governor conrtrolled throttle valve, a pivoted lever,` linkage conneofingmsaid` lever to said second throttle 'valvefa piston connected to said lever on one side of its pivot,` means for moving saidpiston under fluctuations in discharge pressure ofthe compressor, means to unload the compressor at pre-` determined maximum high pressure and to load the compressor at predetermined low pressure, means connected to said lever at the sideoi? its pivot opposite `to the `side to whchsaid piston is connected,` pressure actuated means for moving said llast-namedmeans, a pressure fluid deliver- 1 l ing conduit connecting said pressure actuated means and `said compressor` loading and unloading means whereby the compressor loading and unloadingmeansiwill controloperation of the pressure actuated means,` and tensioning means connected to said lever to apply a predetermined tension to the leverrin opposition to movement I ofthe lever by said piston.

15.` In a speed regulator foran engine driven fluid compressor having a throttle valve controlled by the governor, of a` second throttle valve operable independently of the governor controlled throttle valve; la pivoted leverl linkage connect- 12 a. frlctionless and universal centering device carried by said piston and engaging said cylinder, said piston being free from peripheral engagement with said cylinder, said frictionless and universa1 centering device comprising a carrying body having a plurality of circumferentially spaced recesses in its perimeter, bearing balls in saidrecesses, and spring members engaging said connecting'said piston to said lever to actuate the lever during movement of the piston in one di# rection and permit movement of the lever independently of movement of the piston.

16. In a speed regulator for anfengine driven iluidy compressor having a throttle valve controlled by the governor, of asecond throttle valve operable independently of the governor controlled throttle valve, apivoted lever, linkageconnecting said lever to said second throttle valve, a control cylinder, a piston in said cylinder for reciprocatory movement therein, a. flexible diaphragm in the cylinder and engaging said piston,`

a conduit for`delivering pressure iluid to said cylinder for actuating said diaphragm to move said piston, tensioned means for opposing operation of said piston by said diaphragm, means connecting said piston to said lever to actuate the lever during movement of the piston in one direction and permit movement of the lever independently of movement of the piston, said piston being connected to said lever at one side of its pivot, a rod connected to said lever at the side of its pivot opposite to the side to which the piston is connected, pressure actuated means for movingsaid rod, and a pressure fluid delivering conduit con-Y necting said pressure actuated means and compressor loading and unloading means whereby the compressor loading and unloading means will control movement of said rod.

17. In a speed regulator for an engine driven iluid compressor having a throttle valve controlled by the governor,. of a second throttle lvalve operable independently of the governor controlled throttle valve, a pivoted leverl linkage connecting said lever to said .second throttle valye, a control cylinder, a piston in said cylinder for reciprocatory movement therein, a flexible diaphragm in the cylinder and engaging said piston, a conduit for delivering pressure fluid to said cylinder for actuating said diaphragm to move said piston, tensioned means for opposing operation of said piston by said diaphragm, means connecting said piston to said lever to actuate the lever during movement of the piston in one direction and permit movement of the lever independently of movement of the piston, and a frictionless and universal centering device carried by said piston and engaging said cylinder. i

18. In a speed regulator for an engine driven uid compressor having a, throttle valve controlled by the governor, of a' second throttle valve operable independently of the governor controlled throttle valve, a pivoted lever, linkage connecting said lever to said second throttle valve, a control cylinder, a piston in said cylinder for reciprocatory movement therein, a flexible diaphragm in the cylinder and engaging said piston, a conduit for delivering pressure fluid to said cylinder for actuating said diaphragm to move said piston, tensioned means for opposing operation of said piston by said diaphragm, means connecting said piston to said lever to actuate the lever during movement of the piston in one direction and permit movement of the lever independently of movement of the piston,

bearing balls upon each side of said carrying body to yieldably maintain the balls in position to provide a frictionless and universal centering of the piston in the cylinder.

19. In a speed regulator for an engine driven riluid compressor having a throttle valve controlled by the governor, of a second throttle valve operable` independently of the governor controlled throttle valve, a pivoted lever, linkage connecting said lever to said second throttle valve, a. control cylinder, a piston in said cylinder for reciprocatory movement therein, a ilexible diaphragm in the cylinder and engaging said piston, a conduit yfor delivering pressure fluid to said cylinder for actuating said diaphragmk to move said piston, tensioned means for opposing operation oi said piston by said diaphragm, means connecting said piston to said lever to actuate the lever during movement of the piston in one direction and permit movement of the lever independently of movement of the piston, said piston and lever connecting means being connected to the lever on one side of its pivot, an operating rod connected to said lever at the side of its pivot opposite to the side to which the piston is connected, a second diaphragm carried by said cylinder, means for leading pressure fiuid from a point diierent from and under different control conditions than the point of delivery and control of the pressure fluid f which actuates said first diaphragmfor actuating said second diaphragm, and means operated by said second diaphragm for operating said rod.

20. In a speed regulator for an engine driven fluid compressor having a throttle valve controlled by the governor, of la second throttle valve operable independently of the governor controlled throttle valve, a pivoted lever, linkage connecting said lever to said second throttle valve, a' control cylinder, a piston in said cylinder for reciprocatory movement therein, a ilexible diaphragm in the cylinder and engaging said piston, a conduit for delivering pressure fluid to said cylinder for actuating said diaphragm to move said piston, tensioned means for opposing operation of said piston by said diaphragm, means connecting said piston to said lever to actuate the lever during movement of the piston l in one direction and permit movement of the lever independently of movement of the piston, said piston and lever connecting means being connected to the lever on one side of its pivot, an operating rod connected to said lever at the side of its pivot opposite to the side to which the piston is connected, a second diaphragm carried by said cylinder, means for leading pressure iluid from a point different from and under differentl control conditions than the point of delivery and control of the pressure fluid which actuates said ilrst diaphragm for actuating said second diaphragm, means operated by said second diaphragm for operating said rod, adjustable means providing a slip connection between said rod and lever, and tensioning means connected to said lever to apply a predetermined tension to the lever in opposition to movement of the lever by said piston.

connecting said lever to said second throttle valve, a piston connected to said. lever on one side of its pivot, means for moving said piston n under fluctuations in discharge pressure of the compressor, means to unload the compressor-at predetermined maximum high pressure and to load the compressor at predetermined low pressure,`means connected to said lever at the side of its pivot opposite to the side to which said piston is connected, pressure actuated means for moving said last-named means, a pressure uid delivering conduit connecting said pressure actuated means and said compressor loading and unloading means whereby the compressor loading and unloading means will control o'peration of the pressure actuated means, a spiral spring 'connected to said lever to apply tension to the lever in opposition to its movement by said piston, andadjustable means for regulating the number of the coils of said spiral spring which are active thereby regulating the tension applied to the lever.

22. In a speed regulator for an engine driven iluid compressor having a throttle valve contensioned means for opposing operation of said piston by said diaphragm, means connectingsaid piston to said lever to actuate they lever during movement of the piston in one direction and permit movement of the lever independently of movement of the piston, said piston and lever connecting means being connected to the lever on one side of its pivot. an operating rod connected to said lever at the side o1' its pivot opposite to the side to which.. the piston is connected, a second diaphragm carried by said cylinder. means fdr leading pressure iiuid from a point different from and under diierent control conditions than the point of delivery and control of the pressure fluid which actuates said first diaphragm for actuating said second diaphragm, and means operated by said second diaphragm for operating .said rod. a

trolled by the governor, of a second throttle valve j actuating said diaphragm to move said piston,

spiral spring connected to said lever to apply tension to the lever in opposition to movement of the lever by said piston, adjustable means for regulating the number of coils of said spiral spring which are active to apply tension to the lever thereby regulating the tension applied to the lever.

STEVEN F. EVELYN.

REFERENCES CITED The following references are of record in the file of this patent:

` UNrrEn sTA'rEs PATENTS Date 

